Abstract
The synthesis and release of juvenile hormone (JH) is important to regulate growth, metamorphosis, and reproduction in insects. Previously, it has been reported that intracellular calcium is an important modulator to regulate the JH biosynthesis. However, the mechanisms of increased intracellular calcium are unclear. Here, we demonstrated the effects of glutamate, NMDA and kainate on changes in the intracellular calcium in the neuroendocrine cells of adult female viviparus cockroach, Diploptera punctata, using single-cell dual-wavelength microfluorometry and the calcium-sensitive indicator Indo-1. A rapid rise in [Ca2+]i occurred during 60 seconds exposure to glutamate, NMDA or kainate. The NMDA induced changes in [Ca2+]i were abolished, if cells were incubated in solution containing NMDA receptors antagonists, Mg2+ or MK-801. Removal of extracellular calcium also abolished the response to NMDA. These results suggest the presence of NMDA type glutamate receptors on CA cells and the regulation of calcium influx by NMDA receptors may mediate rates of JH synthesis.